Plasma and Fusion Research

Volume 3, S1056 (2008)

Regular Articles

Neoclassical Transport Properties in High-Ion-Temperature Hydrogen Plasmas in the Large Helical Device (LHD)
Seikichi MATSUOKA, Masayuki YOKOYAMA1), Kenichi NAGAOKA1), Yasuhiko TAKEIRI1), Mikiro YOSHINUMA1), Katsumi IDA1), Tetsuo SEKI1), Hisamichi FUNABA1), Sadayoshi MURAKAMI, Atsushi FUKUYAMA, Nobuyoshi OHYABU1), Osamu KANEKO1) and the LHD Experimental Group1)
Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 21 November 2007 / Accepted 24 January 2008 / Published 1 August 2008)

Abstract

High ion temperature (Ti) hydrogen plasmas were successfully demonstrated in the LHD in an experimental campaign (FY2006). The power increase of the perpendicular neutral beam injections (NBIs) has mainly contributed to this achievement. Ti exceeded 5 keV at the average plasma density (ne) of 1.2 × 1019 m-3 and also achieved 3 keV at ne > 3 × 1019 m-3. Neoclassical (NC) analysis was performed for such plasmas. We confirmed that even if Ti or the plasma density became higher, NC transport was remained to a certain value because of the existence of the ambipolar radial electric field (Er), which was roughly two orders of magnitude smaller for cases not involving the existence of ambipolar Er. Besides, a Ti and ne scan of discharge 75235 was also performed to consider the plasma parameter dependence of NC transport. Using these calculations, it is shown that NC ion thermal diffusivities are reduced to a small percentage of NC electron thermal diffusivites even at the fusion reactor relevant parameters such as ne ∼ 1 × 1020 m-3 and Ti ∼ Te ∼ 10 keV.

Keywords

high-ion-temperature, neoclassical transport, radial electric field, GSRAKE code, electron-root

DOI: 10.1585/pfr.3.S1056

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References

  • [1] K. Nagaoka et al., presented at the 16th International Stellarator/Heliotron Workshop, 17th International Toki Conference (2007); M. Yokoyama et al., presented at the 49th APSDPP Annual meeting, Nov. 2007.
  • [2] K. Ida et al., Phys. Rev. Lett. 91, 085003 (2003).
  • [3] C.D. Beidler et al., Plasma Phys. Control. Fusion 37, 463 (1995).
  • [4] M. Yokoyama et al., Nucl. Fusion 45, 1600 (2005).

This paper may be cited as follows:

Seikichi MATSUOKA, Masayuki YOKOYAMA, Kenichi NAGAOKA, Yasuhiko TAKEIRI, Mikiro YOSHINUMA, Katsumi IDA, Tetsuo SEKI, Hisamichi FUNABA, Sadayoshi MURAKAMI, Atsushi FUKUYAMA, Nobuyoshi OHYABU, Osamu KANEKO and the LHD Experimental Group, Plasma Fusion Res. 3, S1056 (2008).